Tower cranes and communication towers are examples of frame structures. Frames are made from bars joined together to form a 'framework'. This is one of the most economical ways of building structures. Some modern buildings have a frame structure which can only be seen during construction. Others are designed to make the 'frame' a feature of the design.

Other structures are formed in quite a different way. The body of a car, for example, is assembled from shaped panels and is called a shell structure.

The ability to see beyond the skin (the covering) of a building; beyond the surfaces of a space and into the load-bearing structure is important to understanding frame structures.